Aliens are more dynamic and... IDK friendlier.Maybe it's because of all the overgrowth everywhere.

Marines are cold, metal, and industrious.

That's really a standpoint on the story, but gameplay-wise I preffer Aliens too.The amount of things you can do in terms of upgrade and evolution is amazing.There's a vast amount of combinations that are all unique in their own way.Like a Skulk that can see through walls vs. a Skulk with phantom.The Skulk chose seeing where the enemies are first over not being seen at all.The Phantom Skulk would rather move quietly and grab the element of suprise.

Aliens by far. When I'm playing as the Marines on most parts it feels like I'm playing "a normal FPS game" and the worst part is that nothing is really good. I mean the weapons, aiming, maps, etc. feel awkwardly mediocre. When I'm playing as the Kharaa NS2 shows it's uniqueness a lot better.